1. Field of the Invention
The present invention relates to containers, trailers or other carriers for transporting goods and having a carriage with wheels that can be moved from underneath the compartment to another position.
2. Description of Related Art
Goods are often transported by trailer or in a container. Containers may be loaded onto on a separate trailer having a flat bed and transported by a truck tractor. The container can also be hoisted off the trailer and loaded onto another carrier such as a cargo ship (and vice versa). A disadvantage with having a container separate from the trailer bed is the high capital cost involved with keeping and maintaining the separate trailers. Also, much time is spent coordinating and moving the trailers so that they can be brought together with a container. Furthermore, when not in use, these trailers take up significant real estate.
In principle, a trailer having a compartment and underlying wheels could be hoisted together onto or off a cargo ship. Unfortunately however, the wheel carriage wastes valuable space, because it effectively raises the compartment some five feet off any loading surface. Thus trailers with wheels cannot be efficiently stacked and loaded.
In U.S. Pat. No. 3,156,484 a wheel assembly is connected through one hydraulic cylinder to the top rear corner of a container and through another hydraulic cylinder to a the side of the container, near the bottom edge. One hydraulic cylinder can slide the wheel assembly from underneath the container, while the other cylinder can lower the container. When the container is lowered, the wheel assembly tilts up at about 45.degree. and does not lay flat against the back of the container. Thus this wheel assembly is not designed to be shipped width the container is specifically described as being removed after the container is lowered.
U.S. Pat. No. 5,050,897 shows a set of wheels that swing on a pivot point from a deployed position underneath the trailer to a stored position inside the trailer body. This structure effectively extends the length of the trailer by adding unusable space that is dedicated to wheel storage, not cargo storage.
U.S. Pat. No. 3,193,301 shows a transporter assembly that can lift a unit by swinging in about a pivot point at the upper edge of the unit. Again, this structure shows wheels that retract, but do not store compactly and would not be shipped with the unit. See also U.S. Pat. Nos. 3,570,694 and 4,321,709.
U.S. Pat. No. 3,788,683 shows dolly wheels that are deployed from cavities on the underside of a container, but this structure would not be useful for highway transportation. Moreover, the space needed for the stored dolly wheels will create an obstruction in the container.
German reference 1,047,032 shows a trailer with wheels that can be shifted backwardly before being lifted to an aft position. It is unclear whether this reference reveals mechanical structure that operates effectively and efficiently.